What is as graceful and beautiful as a butterfly, as ferocious as the most dangerous predator, and delivers a painful sting with its venomous spines? Answer: the lionfish, an invasive species of fish from the Indian and western Pacific Oceans that is now found off the mid-Atlantic coast of the United States. This new educational case study from the National Oceanic and Atmospheric Administration (NOAA) examines how the lionfish became an invasive species–one that has been “transported by natural processes or human activities, either intentionally or accidentally, into a region where it did not occur previously and reproduces … causing economic or environmental harm or harm to human health.” Invasive species like the lionfish are becoming a major problem in many parts of the world. Now, scientists are using newly collected data and technology to determine how an “alien invasion” affects an ecosystem. At this web site, students can learn about the environmental and economic consequences of invasive species, using the recent invasion of the lionfish as a case study. In the process, they’ll explore the role of the aquarium trade in the invasion, and whether the invasion can be curbed. Also available are a student and teacher guide, an interactive quiz, and more. This Discovery Story on lionfish is the first of several educational case studies NOAA is producing to improve students’ understanding of ocean science and the changing Earth.